refactor chat components to improve state management and enhance UI responsiveness; replace ChatInputBar with ChatInputWithMentions, and update ChatSidebar and TabBar for better tab handling

apps/x/apps/renderer/src/components/chat-input-with-mentions.tsx

@@ -0,0 +1,195 @@
+import { useCallback, useEffect } from 'react'
+import { ArrowUp, LoaderIcon, Square } from 'lucide-react'
+
+import { Button } from '@/components/ui/button'
+import { cn } from '@/lib/utils'
+import {
+  type FileMention,
+  type PromptInputMessage,
+  PromptInputProvider,
+  PromptInputTextarea,
+  usePromptInputController,
+} from '@/components/ai-elements/prompt-input'
+
+interface ChatInputInnerProps {
+  onSubmit: (message: PromptInputMessage, mentions?: FileMention[]) => void
+  onStop?: () => void
+  isProcessing: boolean
+  isStopping?: boolean
+  presetMessage?: string
+  onPresetMessageConsumed?: () => void
+  runId?: string | null
+  initialDraft?: string
+  onDraftChange?: (text: string) => void
+}
+
+function ChatInputInner({
+  onSubmit,
+  onStop,
+  isProcessing,
+  isStopping,
+  presetMessage,
+  onPresetMessageConsumed,
+  runId,
+  initialDraft,
+  onDraftChange,
+}: ChatInputInnerProps) {
+  const controller = usePromptInputController()
+  const message = controller.textInput.value
+  const canSubmit = Boolean(message.trim()) && !isProcessing
+
+  // Restore the tab draft when this input mounts.
+  useEffect(() => {
+    if (initialDraft) {
+      controller.textInput.setInput(initialDraft)
+    }
+    // eslint-disable-next-line react-hooks/exhaustive-deps
+  }, [])
+
+  useEffect(() => {
+    onDraftChange?.(message)
+  }, [message, onDraftChange])
+
+  useEffect(() => {
+    if (presetMessage) {
+      controller.textInput.setInput(presetMessage)
+      onPresetMessageConsumed?.()
+    }
+  }, [presetMessage, controller.textInput, onPresetMessageConsumed])
+
+  const handleSubmit = useCallback(() => {
+    if (!canSubmit) return
+    onSubmit({ text: message.trim(), files: [] }, controller.mentions.mentions)
+    controller.textInput.clear()
+    controller.mentions.clearMentions()
+  }, [canSubmit, message, onSubmit, controller])
+
+  const handleKeyDown = useCallback((e: React.KeyboardEvent) => {
+    if (e.key === 'Enter' && !e.shiftKey) {
+      e.preventDefault()
+      handleSubmit()
+    }
+  }, [handleSubmit])
+
+  useEffect(() => {
+    const onDragOver = (e: DragEvent) => {
+      if (e.dataTransfer?.types?.includes('Files')) {
+        e.preventDefault()
+      }
+    }
+
+    const onDrop = (e: DragEvent) => {
+      if (e.dataTransfer?.types?.includes('Files')) {
+        e.preventDefault()
+      }
+      if (e.dataTransfer?.files && e.dataTransfer.files.length > 0) {
+        const paths = Array.from(e.dataTransfer.files)
+          .map((file) => window.electronUtils?.getPathForFile(file))
+          .filter(Boolean)
+        if (paths.length > 0) {
+          const currentText = controller.textInput.value
+          const pathText = paths.join(' ')
+          controller.textInput.setInput(currentText ? `${currentText} ${pathText}` : pathText)
+        }
+      }
+    }
+
+    document.addEventListener('dragover', onDragOver)
+    document.addEventListener('drop', onDrop)
+    return () => {
+      document.removeEventListener('dragover', onDragOver)
+      document.removeEventListener('drop', onDrop)
+    }
+  }, [controller])
+
+  return (
+    <div className="flex items-center gap-2 rounded-lg border border-border bg-background px-4 py-4 shadow-none">
+      <PromptInputTextarea
+        placeholder="Type your message..."
+        onKeyDown={handleKeyDown}
+        autoFocus
+        focusTrigger={runId}
+        className="min-h-6 rounded-none border-0 py-0 shadow-none focus-visible:ring-0"
+      />
+      {isProcessing ? (
+        <Button
+          size="icon"
+          onClick={onStop}
+          title={isStopping ? 'Click again to force stop' : 'Stop generation'}
+          className={cn(
+            'h-7 w-7 shrink-0 rounded-full transition-all',
+            isStopping
+              ? 'bg-destructive text-destructive-foreground hover:bg-destructive/90'
+              : 'bg-primary text-primary-foreground hover:bg-primary/90'
+          )}
+        >
+          {isStopping ? (
+            <LoaderIcon className="h-4 w-4 animate-spin" />
+          ) : (
+            <Square className="h-3 w-3 fill-current" />
+          )}
+        </Button>
+      ) : (
+        <Button
+          size="icon"
+          onClick={handleSubmit}
+          disabled={!canSubmit}
+          className={cn(
+            'h-7 w-7 shrink-0 rounded-full transition-all',
+            canSubmit
+              ? 'bg-primary text-primary-foreground hover:bg-primary/90'
+              : 'bg-muted text-muted-foreground'
+          )}
+        >
+          <ArrowUp className="h-4 w-4" />
+        </Button>
+      )}
+    </div>
+  )
+}
+
+export interface ChatInputWithMentionsProps {
+  knowledgeFiles: string[]
+  recentFiles: string[]
+  visibleFiles: string[]
+  onSubmit: (message: PromptInputMessage, mentions?: FileMention[]) => void
+  onStop?: () => void
+  isProcessing: boolean
+  isStopping?: boolean
+  presetMessage?: string
+  onPresetMessageConsumed?: () => void
+  runId?: string | null
+  initialDraft?: string
+  onDraftChange?: (text: string) => void
+}
+
+export function ChatInputWithMentions({
+  knowledgeFiles,
+  recentFiles,
+  visibleFiles,
+  onSubmit,
+  onStop,
+  isProcessing,
+  isStopping,
+  presetMessage,
+  onPresetMessageConsumed,
+  runId,
+  initialDraft,
+  onDraftChange,
+}: ChatInputWithMentionsProps) {
+  return (
+    <PromptInputProvider knowledgeFiles={knowledgeFiles} recentFiles={recentFiles} visibleFiles={visibleFiles}>
+      <ChatInputInner
+        onSubmit={onSubmit}
+        onStop={onStop}
+        isProcessing={isProcessing}
+        isStopping={isStopping}
+        presetMessage={presetMessage}
+        onPresetMessageConsumed={onPresetMessageConsumed}
+        runId={runId}
+        initialDraft={initialDraft}
+        onDraftChange={onDraftChange}
+      />
+    </PromptInputProvider>
+  )
+}

apps/x/apps/renderer/src/components/chat-sidebar.tsx

@@ -1,13 +1,11 @@
-import { useCallback, useEffect, useMemo, useRef, useState } from 'react'
-import { ArrowUp, Expand, LoaderIcon, SquarePen, Square } from 'lucide-react'
+import React, { useCallback, useEffect, useMemo, useRef, useState } from 'react'
+import { Expand, Minimize2, SquarePen } from 'lucide-react'
 import type { ToolUIPart } from 'ai'
+import z from 'zod'
+
 import { Button } from '@/components/ui/button'
 import { cn } from '@/lib/utils'
-import {
-  Tooltip,
-  TooltipContent,
-  TooltipTrigger,
-} from '@/components/ui/tooltip'
+import { Tooltip, TooltipContent, TooltipTrigger } from '@/components/ui/tooltip'
 import {
   Conversation,
   ConversationContent,
@@ -19,22 +17,17 @@ import {
   MessageContent,
   MessageResponse,
 } from '@/components/ai-elements/message'
-
 import { Shimmer } from '@/components/ai-elements/shimmer'
 import { Tool, ToolContent, ToolHeader, ToolInput, ToolOutput } from '@/components/ai-elements/tool'
 import { PermissionRequest } from '@/components/ai-elements/permission-request'
 import { AskHumanRequest } from '@/components/ai-elements/ask-human-request'
 import { Suggestions } from '@/components/ai-elements/suggestions'
 import { type PromptInputMessage, type FileMention } from '@/components/ai-elements/prompt-input'
-import { useMentionDetection } from '@/hooks/use-mention-detection'
-import { MentionPopover } from '@/components/mention-popover'
-import { toKnowledgePath, wikiLabel } from '@/lib/wiki-links'
-import { getMentionHighlightSegments } from '@/lib/mention-highlights'
 import { ToolPermissionRequestEvent, AskHumanRequestEvent } from '@x/shared/src/runs.js'
-import z from 'zod'
-import React from 'react'
 import { FileCardProvider } from '@/contexts/file-card-context'
 import { MarkdownPreOverride } from '@/components/ai-elements/markdown-code-override'
+import { TabBar, type ChatTab } from '@/components/tab-bar'
+import { ChatInputWithMentions } from '@/components/chat-input-with-mentions'
 
 interface ChatMessage {
   id: string
@@ -61,6 +54,14 @@ interface ErrorMessage {
 
 type ConversationItem = ChatMessage | ToolCall | ErrorMessage
 
+type ChatTabViewState = {
+  conversation: ConversationItem[]
+  currentAssistantMessage: string
+  pendingAskHumanRequests: Map<string, z.infer<typeof AskHumanRequestEvent>>
+  allPermissionRequests: Map<string, z.infer<typeof ToolPermissionRequestEvent>>
+  permissionResponses: Map<string, 'approve' | 'deny'>
+}
+
 type ToolState = 'input-streaming' | 'input-available' | 'output-available' | 'output-error'
 
 const isChatMessage = (item: ConversationItem): item is ChatMessage => 'role' in item
@@ -107,28 +108,60 @@ const normalizeToolOutput = (output: ToolCall['result'] | undefined, status: Too
 
 const streamdownComponents = { pre: MarkdownPreOverride }
 
-const MIN_WIDTH = 300
-const MAX_WIDTH = 700
-const DEFAULT_WIDTH = 400
+const MIN_WIDTH = 360
+const MAX_WIDTH = 1600
+const MIN_MAIN_PANE_WIDTH = 420
+const MIN_MAIN_PANE_RATIO = 0.3
+const DEFAULT_WIDTH = 460
+const RIGHT_PANE_WIDTH_STORAGE_KEY = 'x:right-pane-width'
+
+function clampPaneWidth(width: number, maxWidth: number = MAX_WIDTH): number {
+  const boundedMax = Math.max(0, Math.min(MAX_WIDTH, maxWidth))
+  const boundedMin = Math.min(MIN_WIDTH, boundedMax)
+  return Math.min(boundedMax, Math.max(boundedMin, width))
+}
+
+function getInitialPaneWidth(defaultWidth: number): number {
+  const fallback = clampPaneWidth(defaultWidth)
+  if (typeof window === 'undefined') return fallback
+  try {
+    const raw = window.localStorage.getItem(RIGHT_PANE_WIDTH_STORAGE_KEY)
+    if (!raw) return fallback
+    const parsed = Number(raw)
+    if (!Number.isFinite(parsed)) return fallback
+    return clampPaneWidth(parsed)
+  } catch {
+    return fallback
+  }
+}
 
 interface ChatSidebarProps {
   defaultWidth?: number
   isOpen?: boolean
-  onNewChat: () => void
+  isMaximized?: boolean
+  chatTabs: ChatTab[]
+  activeChatTabId: string
+  getChatTabTitle: (tab: ChatTab) => string
+  isChatTabProcessing: (tab: ChatTab) => boolean
+  onSwitchChatTab: (tabId: string) => void
+  onCloseChatTab: (tabId: string) => void
+  onNewChatTab: () => void
   onOpenFullScreen?: () => void
   conversation: ConversationItem[]
   currentAssistantMessage: string
+  chatTabStates?: Record<string, ChatTabViewState>
   isProcessing: boolean
   isStopping?: boolean
   onStop?: () => void
-  message: string
-  onMessageChange: (message: string) => void
   onSubmit: (message: PromptInputMessage, mentions?: FileMention[]) => void
   knowledgeFiles?: string[]
   recentFiles?: string[]
   visibleFiles?: string[]
-  selectedPath?: string | null
-  pendingPermissionRequests?: Map<string, z.infer<typeof ToolPermissionRequestEvent>>
+  runId?: string | null
+  presetMessage?: string
+  onPresetMessageConsumed?: () => void
+  initialDraft?: string
+  onDraftChange?: (text: string) => void
   pendingAskHumanRequests?: Map<string, z.infer<typeof AskHumanRequestEvent>>
   allPermissionRequests?: Map<string, z.infer<typeof ToolPermissionRequestEvent>>
   permissionResponses?: Map<string, 'approve' | 'deny'>
@@ -140,20 +173,30 @@ interface ChatSidebarProps {
 export function ChatSidebar({
   defaultWidth = DEFAULT_WIDTH,
   isOpen = true,
-  onNewChat,
+  isMaximized = false,
+  chatTabs,
+  activeChatTabId,
+  getChatTabTitle,
+  isChatTabProcessing,
+  onSwitchChatTab,
+  onCloseChatTab,
+  onNewChatTab,
   onOpenFullScreen,
   conversation,
   currentAssistantMessage,
+  chatTabStates = {},
   isProcessing,
   isStopping,
   onStop,
-  message,
-  onMessageChange,
   onSubmit,
   knowledgeFiles = [],
   recentFiles = [],
   visibleFiles = [],
-  selectedPath,
+  runId,
+  presetMessage,
+  onPresetMessageConsumed,
+  initialDraft,
+  onDraftChange,
   pendingAskHumanRequests = new Map(),
   allPermissionRequests = new Map(),
   permissionResponses = new Map(),
@@ -161,91 +204,62 @@ export function ChatSidebar({
   onAskHumanResponse,
   onOpenKnowledgeFile,
 }: ChatSidebarProps) {
-  const [width, setWidth] = useState(defaultWidth)
+  const [width, setWidth] = useState(() => getInitialPaneWidth(defaultWidth))
   const [isResizing, setIsResizing] = useState(false)
   const [showContent, setShowContent] = useState(isOpen)
+  const [localPresetMessage, setLocalPresetMessage] = useState<string | undefined>(undefined)
+
+  const paneRef = useRef<HTMLDivElement>(null)
+  const startXRef = useRef(0)
+  const startWidthRef = useRef(0)
+
+  const getMaxAllowedWidth = useCallback(() => {
+    if (typeof window === 'undefined') return MAX_WIDTH
+    const paneElement = paneRef.current
+    const splitContainer = paneElement?.parentElement
+    const mainPane = splitContainer?.querySelector<HTMLElement>('[data-slot="sidebar-inset"]')
+    const paneWidth = paneElement?.getBoundingClientRect().width ?? 0
+    const mainPaneWidth = mainPane?.getBoundingClientRect().width ?? 0
+    const splitWidth = paneWidth + mainPaneWidth
+    const fallbackWidth = splitContainer?.clientWidth ?? window.innerWidth
+    const availableSplitWidth = splitWidth > 0 ? splitWidth : fallbackWidth
+    const minMainPaneWidth = Math.min(
+      availableSplitWidth,
+      Math.max(
+        MIN_MAIN_PANE_WIDTH,
+        Math.floor(availableSplitWidth * MIN_MAIN_PANE_RATIO)
+      )
+    )
+    return Math.max(0, availableSplitWidth - minMainPaneWidth)
+  }, [])
 
-  // Delay showing content when opening, hide immediately when closing
   useEffect(() => {
     if (isOpen) {
       const timer = setTimeout(() => setShowContent(true), 150)
       return () => clearTimeout(timer)
-    } else {
-      setShowContent(false)
     }
+    setShowContent(false)
   }, [isOpen])
-  const startXRef = useRef(0)
-  const startWidthRef = useRef(0)
-  const textareaRef = useRef<HTMLTextAreaElement>(null)
-  const containerRef = useRef<HTMLDivElement>(null)
-  const highlightRef = useRef<HTMLDivElement>(null)
-  const [mentions, setMentions] = useState<FileMention[]>([])
-  const autoMentionRef = useRef<{ path: string; displayName: string } | null>(null)
-  const lastSelectedPathRef = useRef<string | null>(null)
-
-  // Build mention labels for highlighting (handles multi-word names like "AI Agents")
-  const mentionLabels = useMemo(() => {
-    if (knowledgeFiles.length === 0) return []
-    const labels = knowledgeFiles
-      .map((path) => wikiLabel(path))
-      .map((label) => label.trim())
-      .filter(Boolean)
-    return Array.from(new Set(labels))
-  }, [knowledgeFiles])
-
-  const { activeMention, cursorCoords } = useMentionDetection(
-    textareaRef,
-    message,
-    knowledgeFiles.length > 0
-  )
-
-  // Use proper regex-based highlight segmentation that handles multi-word names
-  const mentionHighlights = useMemo(
-    () => getMentionHighlightSegments(message, activeMention, mentionLabels),
-    [message, activeMention, mentionLabels]
-  )
-
-  // Sync highlight overlay scroll with textarea
-  const syncHighlightScroll = useCallback(() => {
-    const textarea = textareaRef.current
-    const highlight = highlightRef.current
-    if (!textarea || !highlight) return
-    highlight.scrollTop = textarea.scrollTop
-    highlight.scrollLeft = textarea.scrollLeft
-  }, [])
 
   useEffect(() => {
-    syncHighlightScroll()
-  }, [message, mentionHighlights.hasHighlights, syncHighlightScroll])
+    if (typeof window === 'undefined') return
+    try {
+      window.localStorage.setItem(RIGHT_PANE_WIDTH_STORAGE_KEY, String(width))
+    } catch {
+      // Ignore persistence failures and keep in-memory behavior.
+    }
+  }, [width])
 
-  const handleMentionSelect = useCallback(
-    (path: string, displayName: string) => {
-      if (!activeMention) return
+  useEffect(() => {
+    const clampToAvailableWidth = () => {
+      const maxAllowedWidth = getMaxAllowedWidth()
+      setWidth((prev) => clampPaneWidth(prev, maxAllowedWidth))
+    }
 
-      const beforeAt = message.substring(0, activeMention.triggerIndex)
-      const afterQuery = message.substring(
-        activeMention.triggerIndex + 1 + activeMention.query.length
-      )
-
-      const newText = `${beforeAt}@${displayName} ${afterQuery}`
-      onMessageChange(newText)
-
-      const fullPath = toKnowledgePath(path)
-      if (fullPath) {
-        setMentions(prev => {
-          if (prev.some(m => m.path === fullPath)) return prev
-          return [...prev, { id: `mention-${Date.now()}`, path: fullPath, displayName }]
-        })
-      }
-
-      textareaRef.current?.focus()
-    },
-    [activeMention, message, onMessageChange]
-  )
-
-  const handleMentionClose = useCallback(() => {
-    // The popover handles its own closing
-  }, [])
+    clampToAvailableWidth()
+    window.addEventListener('resize', clampToAvailableWidth)
+    return () => window.removeEventListener('resize', clampToAvailableWidth)
+  }, [getMaxAllowedWidth])
 
   const handleMouseDown = useCallback((e: React.MouseEvent) => {
     e.preventDefault()
@@ -253,10 +267,10 @@ export function ChatSidebar({
     startWidthRef.current = width
     setIsResizing(true)
 
-    const handleMouseMove = (e: MouseEvent) => {
-      const delta = startXRef.current - e.clientX
-      const newWidth = Math.min(MAX_WIDTH, Math.max(MIN_WIDTH, startWidthRef.current + delta))
-      setWidth(newWidth)
+    const handleMouseMove = (event: MouseEvent) => {
+      const delta = startXRef.current - event.clientX
+      const maxAllowedWidth = getMaxAllowedWidth()
+      setWidth(clampPaneWidth(startWidthRef.current + delta, maxAllowedWidth))
     }
 
     const handleMouseUp = () => {
@@ -267,127 +281,33 @@ export function ChatSidebar({
 
     document.addEventListener('mousemove', handleMouseMove)
     document.addEventListener('mouseup', handleMouseUp)
-  }, [width])
+  }, [width, getMaxAllowedWidth])
 
-  // Auto-focus textarea when sidebar opens or when conversation is cleared (new chat)
-  useEffect(() => {
-    // Focus when conversation is empty (new chat started)
-    if (conversation.length === 0) {
-      const timer = setTimeout(() => {
-        textareaRef.current?.focus()
-      }, 50)
-      return () => clearTimeout(timer)
-    }
-  }, [conversation.length])
-
-  // Auto-populate with @currentfile when switching knowledge files
-  useEffect(() => {
-    if (selectedPath === lastSelectedPathRef.current) return
-    lastSelectedPathRef.current = selectedPath ?? null
-
-    if (!selectedPath || !selectedPath.startsWith('knowledge/') || !selectedPath.endsWith('.md')) {
-      return
-    }
-
-    const displayName = wikiLabel(selectedPath)
-    const previousAuto = autoMentionRef.current
-    const trimmed = message.trim()
-    const previousToken = previousAuto ? `@${previousAuto.displayName}` : null
-    const shouldReplace = !trimmed || (previousToken && trimmed === previousToken)
-
-    if (!shouldReplace) {
-      return
-    }
-
-    const nextText = `@${displayName} `
-    if (message !== nextText) {
-      onMessageChange(nextText)
-    }
-
-    setMentions((prev) => {
-      const withoutPrevious = previousAuto
-        ? prev.filter((mention) => mention.path !== previousAuto.path)
-        : prev
-      if (withoutPrevious.some((mention) => mention.path === selectedPath)) {
-        return withoutPrevious
-      }
-      return [
-        ...withoutPrevious,
-        {
-          id: `mention-auto-${Date.now()}`,
-          path: selectedPath,
-          displayName,
-        },
-      ]
-    })
-
-    autoMentionRef.current = { path: selectedPath, displayName }
-  }, [selectedPath, message, onMessageChange])
-
-  const hasConversation = conversation.length > 0 || currentAssistantMessage
-  const canSubmit = Boolean(message.trim()) && !isProcessing
-
-  const handleSubmit = () => {
-    const trimmed = message.trim()
-    if (trimmed && !isProcessing) {
-      onSubmit({ text: trimmed, files: [] }, mentions)
-      setMentions([])
-    }
-  }
-
-  const handleKeyDown = (e: React.KeyboardEvent<HTMLTextAreaElement>) => {
-    // If mention popover is open, let it handle navigation keys
-    if (activeMention && ['ArrowDown', 'ArrowUp', 'Tab', 'Escape'].includes(e.key)) {
-      return
-    }
-
-    if (e.key === 'Enter') {
-      // If mention popover is open, Enter should select the item
-      if (activeMention) {
-        return
-      }
-
-      if (!e.shiftKey) {
-        e.preventDefault()
-        handleSubmit()
-      }
-    }
-
-    // Handle backspace to delete entire mention at once
-    if (e.key === 'Backspace') {
-      const textarea = e.currentTarget
-      const cursorPos = textarea.selectionStart
-      const selectionEnd = textarea.selectionEnd
-
-      // Only handle if no text is selected (cursor is at a single position)
-      if (cursorPos !== selectionEnd) return
-
-      // Check if cursor is right after a mention
-      for (const label of mentionLabels) {
-        const mentionText = `@${label}`
-        const startPos = cursorPos - mentionText.length
-        if (startPos >= 0) {
-          const textBefore = message.substring(startPos, cursorPos)
-          if (textBefore === mentionText) {
-            // Check if it's at word boundary (start of string or preceded by whitespace)
-            if (startPos === 0 || /\s/.test(message[startPos - 1])) {
-              e.preventDefault()
-              const newText = message.substring(0, startPos) + message.substring(cursorPos)
-              onMessageChange(newText)
-              // Remove the mention from state
-              setMentions(prev => prev.filter(m => m.displayName !== label))
-              // Set cursor position after React updates
-              setTimeout(() => {
-                textarea.selectionStart = startPos
-                textarea.selectionEnd = startPos
-              }, 0)
-              return
-            }
-          }
-        }
-      }
-    }
-  }
+  const activeTabState = useMemo<ChatTabViewState>(() => ({
+    conversation,
+    currentAssistantMessage,
+    pendingAskHumanRequests,
+    allPermissionRequests,
+    permissionResponses,
+  }), [
+    conversation,
+    currentAssistantMessage,
+    pendingAskHumanRequests,
+    allPermissionRequests,
+    permissionResponses,
+  ])
+  const emptyTabState = useMemo<ChatTabViewState>(() => ({
+    conversation: [],
+    currentAssistantMessage: '',
+    pendingAskHumanRequests: new Map(),
+    allPermissionRequests: new Map(),
+    permissionResponses: new Map(),
+  }), [])
+  const getTabState = useCallback((tabId: string): ChatTabViewState => {
+    if (tabId === activeChatTabId) return activeTabState
+    return chatTabStates[tabId] ?? emptyTabState
+  }, [activeChatTabId, activeTabState, chatTabStates, emptyTabState])
+  const hasConversation = activeTabState.conversation.length > 0 || Boolean(activeTabState.currentAssistantMessage)
 
   const renderConversationItem = (item: ConversationItem) => {
     if (isChatMessage(item)) {
@@ -410,16 +330,10 @@ export function ChatSidebar({
       const input = normalizeToolInput(item.input)
       return (
         <Tool key={item.id}>
-          <ToolHeader
-            title={item.name}
-            type={`tool-${item.name}`}
-            state={toToolState(item.status)}
-          />
+          <ToolHeader title={item.name} type={`tool-${item.name}`} state={toToolState(item.status)} />
           <ToolContent>
             <ToolInput input={input} />
-            {output !== null ? (
-              <ToolOutput output={output} errorText={errorText} />
-            ) : null}
+            {output !== null ? <ToolOutput output={output} errorText={errorText} /> : null}
           </ToolContent>
         </Tool>
       )
@@ -438,218 +352,188 @@ export function ChatSidebar({
     return null
   }
 
-  const displayWidth = isOpen ? width : 0
+  const paneStyle = useMemo<React.CSSProperties>(() => {
+    if (!isOpen) {
+      return { width: 0, flex: '0 0 auto' }
+    }
+    if (isMaximized) {
+      // In maximize mode the pane should grow into the freed left space,
+      // not add extra width to the right and overflow the app viewport.
+      return { width: 0, flex: '1 1 auto' }
+    }
+    return { width, flex: '0 0 auto' }
+  }, [isOpen, isMaximized, width])
 
   return (
     <div
+      ref={paneRef}
       className={cn(
-        "relative flex flex-col border-l border-border bg-background shrink-0 overflow-hidden",
-        !isResizing && "transition-[width] duration-200 ease-linear"
+        'relative flex min-w-0 flex-col overflow-hidden border-l border-border bg-background',
+        !isResizing && 'transition-[width] duration-200 ease-linear'
       )}
-      style={{ width: displayWidth }}
+      style={paneStyle}
     >
-      {/* Resize handle */}
-      <div
-        onMouseDown={handleMouseDown}
-        className={cn(
-          "absolute inset-y-0 left-0 z-20 w-4 -translate-x-1/2 cursor-col-resize",
-          "after:absolute after:inset-y-0 after:left-1/2 after:w-[2px] after:transition-colors",
-          "hover:after:bg-sidebar-border",
-          isResizing && "after:bg-primary"
-        )}
-      />
+      {!isMaximized && (
+        <div
+          onMouseDown={handleMouseDown}
+          className={cn(
+            'absolute inset-y-0 left-0 z-20 w-4 -translate-x-1/2 cursor-col-resize',
+            'after:absolute after:inset-y-0 after:left-1/2 after:w-[2px] after:transition-colors',
+            'hover:after:bg-sidebar-border',
+            isResizing && 'after:bg-primary'
+          )}
+        />
+      )}
 
-      {/* Content - delayed on open, hidden immediately on close to avoid layout issues during animation */}
       {showContent && (
         <>
-          {/* Header - minimal, expand and new chat buttons */}
-          <header className="titlebar-drag-region flex h-10 shrink-0 items-center justify-end gap-1 px-2 bg-sidebar">
+          <header className="titlebar-drag-region flex h-10 shrink-0 items-stretch border-b border-border bg-sidebar">
+            <TabBar
+              tabs={chatTabs}
+              activeTabId={activeChatTabId}
+              getTabTitle={getChatTabTitle}
+              getTabId={(tab) => tab.id}
+              isProcessing={isChatTabProcessing}
+              onSwitchTab={onSwitchChatTab}
+              onCloseTab={onCloseChatTab}
+            />
             <Tooltip>
               <TooltipTrigger asChild>
-                <Button variant="ghost" size="icon" onClick={onNewChat} className="titlebar-no-drag h-8 w-8 text-muted-foreground hover:text-foreground">
-                  <SquarePen className="h-4 w-4" />
+                <Button
+                  variant="ghost"
+                  size="icon"
+                  onClick={onNewChatTab}
+                  className="titlebar-no-drag my-1 h-8 w-8 shrink-0 text-muted-foreground hover:text-foreground"
+                >
+                  <SquarePen className="size-5" />
                 </Button>
               </TooltipTrigger>
-              <TooltipContent side="bottom">New chat</TooltipContent>
+              <TooltipContent side="bottom">New chat tab</TooltipContent>
             </Tooltip>
             {onOpenFullScreen && (
               <Tooltip>
                 <TooltipTrigger asChild>
-                  <Button variant="ghost" size="icon" onClick={onOpenFullScreen} className="titlebar-no-drag h-8 w-8 text-muted-foreground hover:text-foreground">
-                    <Expand className="h-4 w-4" />
+                  <Button
+                    variant="ghost"
+                    size="icon"
+                    onClick={onOpenFullScreen}
+                    className="titlebar-no-drag my-1 mr-2 h-8 w-8 shrink-0 text-muted-foreground hover:text-foreground"
+                  >
+                    {isMaximized ? <Minimize2 className="size-5" /> : <Expand className="size-5" />}
                   </Button>
                 </TooltipTrigger>
-                <TooltipContent side="bottom">Full screen chat</TooltipContent>
+                <TooltipContent side="bottom">
+                  {isMaximized ? 'Restore two-pane view' : 'Maximize right pane'}
+                </TooltipContent>
               </Tooltip>
             )}
           </header>
 
-      {/* Conversation area */}
-      <FileCardProvider onOpenKnowledgeFile={onOpenKnowledgeFile ?? (() => {})}>
-      <div className="flex min-h-0 flex-1 flex-col relative">
-        <Conversation className="relative flex-1 overflow-y-auto [scrollbar-gutter:stable]">
-          <ScrollPositionPreserver />
-          <ConversationContent className={hasConversation ? "px-4 pb-24" : "px-4 min-h-full items-center justify-center"}>
-            {!hasConversation ? (
-              <ConversationEmptyState className="h-auto">
-                <div className="flex flex-col items-center gap-1 text-center">
-                  <div className="text-sm text-muted-foreground">
-                    Ask anything...
+          <FileCardProvider onOpenKnowledgeFile={onOpenKnowledgeFile ?? (() => {})}>
+            <div className="flex min-h-0 flex-1 flex-col">
+              {chatTabs.map((tab) => {
+                const isActive = tab.id === activeChatTabId
+                const tabState = getTabState(tab.id)
+                const tabHasConversation = tabState.conversation.length > 0 || Boolean(tabState.currentAssistantMessage)
+                return (
+                  <div
+                    key={tab.id}
+                    className={cn('min-h-0 flex-1 flex-col', isActive ? 'flex' : 'hidden')}
+                    data-chat-tab-panel={tab.id}
+                    aria-hidden={!isActive}
+                  >
+                    <Conversation className="relative flex-1 overflow-y-auto [scrollbar-gutter:stable]">
+                      <ScrollPositionPreserver />
+                      <ConversationContent className={tabHasConversation ? 'mx-auto w-full max-w-4xl px-3 pb-28' : 'mx-auto w-full max-w-4xl min-h-full items-center justify-center px-3 pb-0'}>
+                        {!tabHasConversation ? (
+                          <ConversationEmptyState className="h-auto">
+                            <div className="text-sm text-muted-foreground">Ask anything...</div>
+                          </ConversationEmptyState>
+                        ) : (
+                          <>
+                            {tabState.conversation.map((item) => {
+                              const rendered = renderConversationItem(item)
+                              if (isToolCall(item) && onPermissionResponse) {
+                                const permRequest = tabState.allPermissionRequests.get(item.id)
+                                if (permRequest) {
+                                  const response = tabState.permissionResponses.get(item.id) || null
+                                  return (
+                                    <React.Fragment key={item.id}>
+                                      {rendered}
+                                      <PermissionRequest
+                                        toolCall={permRequest.toolCall}
+                                        onApprove={() => onPermissionResponse(permRequest.toolCall.toolCallId, permRequest.subflow, 'approve')}
+                                        onDeny={() => onPermissionResponse(permRequest.toolCall.toolCallId, permRequest.subflow, 'deny')}
+                                        isProcessing={isActive && isProcessing}
+                                        response={response}
+                                      />
+                                    </React.Fragment>
+                                  )
+                                }
+                              }
+                              return rendered
+                            })}
+
+                            {onAskHumanResponse && Array.from(tabState.pendingAskHumanRequests.values()).map((request) => (
+                              <AskHumanRequest
+                                key={request.toolCallId}
+                                query={request.query}
+                                onResponse={(response) => onAskHumanResponse(request.toolCallId, request.subflow, response)}
+                                isProcessing={isActive && isProcessing}
+                              />
+                            ))}
+
+                            {tabState.currentAssistantMessage && (
+                              <Message from="assistant">
+                                <MessageContent>
+                                  <MessageResponse components={streamdownComponents}>{tabState.currentAssistantMessage}</MessageResponse>
+                                </MessageContent>
+                              </Message>
+                            )}
+
+                            {isActive && isProcessing && !tabState.currentAssistantMessage && (
+                              <Message from="assistant">
+                                <MessageContent>
+                                  <Shimmer duration={1}>Thinking...</Shimmer>
+                                </MessageContent>
+                              </Message>
+                            )}
+                          </>
+                        )}
+                      </ConversationContent>
+                    </Conversation>
                   </div>
-                </div>
-              </ConversationEmptyState>
-            ) : (
-              <>
-                {conversation.map(item => {
-                  const rendered = renderConversationItem(item)
-                  // If this is a tool call, check for permission request (pending or responded)
-                  if (isToolCall(item) && onPermissionResponse) {
-                    const permRequest = allPermissionRequests.get(item.id)
-                    if (permRequest) {
-                      const response = permissionResponses.get(item.id) || null
-                      return (
-                        <React.Fragment key={item.id}>
-                          {rendered}
-                          <PermissionRequest
-                            toolCall={permRequest.toolCall}
-                            onApprove={() => onPermissionResponse(permRequest.toolCall.toolCallId, permRequest.subflow, 'approve')}
-                            onDeny={() => onPermissionResponse(permRequest.toolCall.toolCallId, permRequest.subflow, 'deny')}
-                            isProcessing={isProcessing}
-                            response={response}
-                          />
-                        </React.Fragment>
-                      )
-                    }
-                  }
-                  return rendered
-                })}
+                )
+              })}
 
-                {/* Render pending ask-human requests */}
-                {onAskHumanResponse && Array.from(pendingAskHumanRequests.values()).map((request) => (
-                  <AskHumanRequest
-                    key={request.toolCallId}
-                    query={request.query}
-                    onResponse={(response) => onAskHumanResponse(request.toolCallId, request.subflow, response)}
-                    isProcessing={isProcessing}
-                  />
-                ))}
-
-                {currentAssistantMessage && (
-                  <Message from="assistant">
-                    <MessageContent>
-                      <MessageResponse components={streamdownComponents}>{currentAssistantMessage}</MessageResponse>
-                    </MessageContent>
-                  </Message>
-                )}
-
-                {isProcessing && !currentAssistantMessage && (
-                  <Message from="assistant">
-                    <MessageContent>
-                      <Shimmer duration={1}>Thinking...</Shimmer>
-                    </MessageContent>
-                  </Message>
-                )}
-              </>
-            )}
-          </ConversationContent>
-        </Conversation>
-
-        {/* Input area - responsive to sidebar width, matches floating bar position exactly */}
-        <div className="absolute bottom-6 left-14 right-6 z-10" ref={containerRef}>
-          {!hasConversation && (
-            <Suggestions
-              onSelect={(prompt) => {
-                onMessageChange(prompt)
-                setTimeout(() => textareaRef.current?.focus(), 0)
-              }}
-              vertical
-              className="mb-3"
-            />
-          )}
-          <div className="flex items-center gap-2 bg-background border border-border rounded-lg shadow-none px-4 py-2.5">
-            <div className="relative flex-1 min-w-0">
-              {mentionHighlights.hasHighlights && (
-                <div
-                  ref={highlightRef}
-                  aria-hidden="true"
-                  className="pointer-events-none absolute inset-0 z-0 overflow-hidden whitespace-pre-wrap wrap-break-word text-sm text-transparent"
-                >
-                  {mentionHighlights.segments.map((segment, index) =>
-                    segment.highlighted ? (
-                      <span
-                        key={`mention-${index}`}
-                        className="rounded bg-primary/20 text-transparent [box-decoration-break:clone] shadow-[inset_0_0_0_1px_hsl(var(--primary)/0.15),-3px_0_0_hsl(var(--primary)/0.2),3px_0_0_hsl(var(--primary)/0.2),0_-2px_0_hsl(var(--primary)/0.2),0_2px_0_hsl(var(--primary)/0.2)]"
-                      >
-                        {segment.text}
-                      </span>
-                    ) : (
-                      <span key={`text-${index}`}>{segment.text}</span>
-                    )
+              <div className="sticky bottom-0 z-10 bg-background pb-12 pt-0 shadow-lg">
+                <div className="pointer-events-none absolute inset-x-0 -top-6 h-6 bg-linear-to-t from-background to-transparent" />
+                <div className="mx-auto w-full max-w-4xl px-3">
+                  {!hasConversation && (
+                    <Suggestions onSelect={setLocalPresetMessage} className="mb-3 justify-center" />
                   )}
+                  <ChatInputWithMentions
+                    key={activeChatTabId}
+                    knowledgeFiles={knowledgeFiles}
+                    recentFiles={recentFiles}
+                    visibleFiles={visibleFiles}
+                    onSubmit={onSubmit}
+                    onStop={onStop}
+                    isProcessing={isProcessing}
+                    isStopping={isStopping}
+                    presetMessage={localPresetMessage ?? presetMessage}
+                    onPresetMessageConsumed={() => {
+                      setLocalPresetMessage(undefined)
+                      onPresetMessageConsumed?.()
+                    }}
+                    runId={runId}
+                    initialDraft={initialDraft}
+                    onDraftChange={onDraftChange}
+                  />
                 </div>
-              )}
-              <textarea
-                ref={textareaRef}
-                value={message}
-                onChange={(e) => onMessageChange(e.target.value)}
-                onKeyDown={handleKeyDown}
-                onScroll={syncHighlightScroll}
-                placeholder="Ask anything..."
-                rows={1}
-                className="relative z-10 w-full bg-transparent text-sm outline-none placeholder:text-muted-foreground resize-none max-h-32 min-h-6"
-                style={{ fieldSizing: 'content' } as React.CSSProperties}
-              />
+              </div>
             </div>
-            {isProcessing ? (
-              <Button
-                size="icon"
-                onClick={onStop}
-                title={isStopping ? "Click again to force stop" : "Stop generation"}
-                className={cn(
-                  "h-7 w-7 rounded-full shrink-0 transition-all",
-                  isStopping
-                    ? "bg-destructive text-destructive-foreground hover:bg-destructive/90"
-                    : "bg-primary text-primary-foreground hover:bg-primary/90"
-                )}
-              >
-                {isStopping ? (
-                  <LoaderIcon className="h-4 w-4 animate-spin" />
-                ) : (
-                  <Square className="h-3 w-3 fill-current" />
-                )}
-              </Button>
-            ) : (
-              <Button
-                size="icon"
-                onClick={handleSubmit}
-                disabled={!canSubmit}
-                className={cn(
-                  "h-7 w-7 rounded-full shrink-0 transition-all",
-                  canSubmit
-                    ? "bg-primary text-primary-foreground hover:bg-primary/90"
-                    : "bg-muted text-muted-foreground"
-                )}
-              >
-                <ArrowUp className="h-4 w-4" />
-              </Button>
-            )}
-          </div>
-          {knowledgeFiles.length > 0 && (
-            <MentionPopover
-              files={knowledgeFiles}
-              recentFiles={recentFiles}
-              visibleFiles={visibleFiles}
-              query={activeMention?.query ?? ''}
-              position={cursorCoords}
-              containerRef={containerRef}
-              onSelect={handleMentionSelect}
-              onClose={handleMentionClose}
-              open={Boolean(activeMention)}
-            />
-          )}
-        </div>
-      </div>
-      </FileCardProvider>
+          </FileCardProvider>
         </>
       )}
     </div>

apps/x/apps/renderer/src/components/tab-bar.tsx

@@ -20,6 +20,7 @@ interface TabBarProps<T> {
   isProcessing?: (tab: T) => boolean
   onSwitchTab: (tabId: string) => void
   onCloseTab: (tabId: string) => void
+  layout?: 'fill' | 'scroll'
 }
 
 export function TabBar<T>({
@@ -30,9 +31,17 @@ export function TabBar<T>({
   isProcessing,
   onSwitchTab,
   onCloseTab,
+  layout = 'fill',
 }: TabBarProps<T>) {
   return (
-    <div className="titlebar-no-drag flex flex-1 self-stretch min-w-0 overflow-hidden">
+    <div
+      className={cn(
+        'flex flex-1 self-stretch min-w-0',
+        layout === 'scroll'
+          ? 'overflow-x-auto overflow-y-hidden [scrollbar-width:none] [&::-webkit-scrollbar]:hidden'
+          : 'overflow-hidden'
+      )}
+    >
       {tabs.map((tab, index) => {
         const tabId = getTabId(tab)
         const isActive = tabId === activeTabId
@@ -48,12 +57,13 @@ export function TabBar<T>({
               type="button"
               onClick={() => onSwitchTab(tabId)}
               className={cn(
-                "group/tab relative flex items-center gap-1.5 px-3 self-stretch text-xs min-w-0 max-w-[220px] transition-colors",
+                'titlebar-no-drag group/tab relative flex items-center gap-1.5 px-3 self-stretch text-xs transition-colors',
+                layout === 'scroll' ? 'min-w-[140px] max-w-[240px]' : 'min-w-0 max-w-[220px]',
                 isActive
-                  ? "bg-background text-foreground"
-                  : "text-muted-foreground hover:bg-accent/50 hover:text-foreground"
+                  ? 'bg-background text-foreground'
+                  : 'text-muted-foreground hover:bg-accent/50 hover:text-foreground'
               )}
-              style={{ flex: '1 1 0px' }}
+              style={layout === 'scroll' ? { flex: '0 0 auto' } : { flex: '1 1 0px' }}
             >
               {processing && (
                 <span className="size-1.5 shrink-0 rounded-full bg-emerald-500 animate-pulse" />

apps/x/apps/renderer/src/styles/editor.css

@@ -245,6 +245,16 @@
   align-self: center;
 }
 
+/* Keep knowledge text width readable while margins collapse on narrow panes. */
+.tiptap-editor .ProseMirror {
+  width: 100%;
+  max-width: min(56rem, calc(100% - clamp(0.5rem, 2.5vw, 2rem)));
+  margin-left: auto;
+  margin-right: auto;
+  box-sizing: border-box;
+  padding-left: clamp(0.5rem, 1.5vw, 1rem);
+  padding-right: clamp(0.5rem, 1.5vw, 1rem);
+}
 .wiki-link-anchor {
   position: absolute;
   height: 0;